There is presently a growing need for permeable floors that allow water filtration into the subsoil. However, the construction of permeable concrete floors entails serious problems due mainly to their very low bending and compression resistance, and also because they tend to crumble. There is, for instance, the case of concrete without fines that is permeable but crumbles easily.
Mexican patent application No 962170 (abandoned), filed by the same inventors, describes a permeable product that solves this problem. This product can be made with terpolymers, using type 1 cement.
The additive, main purpose of this invention, noticeably improves the characteristics of the former version, which could only be mixed with type 1 cement. Although that version has some limitations, it shows good bending, compression and abrasion resistance. Its limitations are listed below:
it does not meet the resistance requirements for every type of use, so this product can only be used in parking lots, medium and low traffic streets, and pedestrian walkways;
it is very expensive;
its resistance cannot be easily controlled;
it must be packed dry; and
it does not set properly at very low temperatures.
The product of the present invention, when mixed with any type of cement, water and any hard aggregate with granulometries higher than 4 mm, provides a long lasting permeable concrete with high resistance to bending, compression and abrasion, showing excellent performance in any weather with the following advantages:
different proportions lead to different controllable levels of resistance;
it can be packed as a liquid or as a solid;
it is price-competitive with other commonly used pavements;
this new product can be used practically in any kind of weather;
this product does not degrade, because its formula contains silica aluminate, an inorganic material that reacts when combined with cement, providing great resistance to bending, compression and abrasion;
this additive results in a concrete mixture that may be used to make permeable ecological paving stone blocks; and
as a solid, this additive may be packed together with cement and stone aggregate in different ratios, according to the required resistance, for easy Do it Yourself projects.
Generally, the composition of this invention contains the following basic ingredients: dispersing agents, humectants, hydroxypropylethylcellulose, or hydroxypropylmethylcellulose and silica aluminates. It may also contain, depending on the type of product required, some optional ingredients such as water, surfactant, bactericidal and antifoaming agents.
The characteristics of this invention are such that upon contacting with cement and water, a chemical reaction occurs, giving as a result that the cement adhesiveness increases. The contact points of the aggregate will be very strong, resulting in a product with great cohesion despite the lack of fines such as sand.
In the construction of permeable surfaces some stone aggregates such as, andecite, basalt, vesicular basalt, volcanic red stone, rhyolite, microdiorite, granite, limestone, barite, marble, silica and, in general, any other stone aggregates have been successfully tried. However, it is important to mention that slags can substitute stone aggregates.
The product obtained by using the additive of the this invention can be structurally reinforced with either metal or plastic in the form of rods or meshes.
The lack of fines results in a material with high permeability and no deformation due to temperature variations.
High resistance permeable concretes obtained by using the additive of this invention can be used to build pedestrian paths, walkways and sidewalks, plazas, borders, parking lots, street and highway pavement, retaining walls, breakwater tops, wharf tops, paths for sown lands to improve pest control, cattle corral floors, highways and runways that prevent hydroplaning, and permeable slabs.
And, in general, for any purpose that requires a permeable high strength surface, either to allow water to pass through into the ground or to channel it and take it elsewhere, and which, in addition, makes it possible to reduce or eliminate storm drains.
The additive, which is the main purpose of this invention, can be packed in tank trucks, drums, cans and/or buckets, facilitating its further use, when mixed with cement, stone aggregate and water, to obtain a permeable concrete.
According to the previous description, an additive formula to make permeable concretes with high compression, bending and abrasion resistance is provided.
Of course, the proportions used when mixing different ingredients will basically depend on the product""s end use or application. Different proportions will lead to concretes with different resistance, according to the following formulation:
The formulation to produce 100 kg of additive is:
The following materials are required to produce 1 m3 of permeable concrete:
The following materials are required to produce a solid additive mix:
The additive ingredients provide the following advantages:
Once the dispersing agents, humectant, non ionic and anionic surfactants are mixed with cement, they provide a very effective aggregate reduction which increases the ecological permeable concrete""s resistance to bending, compression and abrasion.
Non crystalline calcinated highly reactive silica aluminate is an inorganic material that due to its characteristics causes a reaction with cement, providing the ecological permeable concrete with a significant increase in bending, compression and abrasion resistance.
Because non crystalline calcinated highly reactive silica aluminate is an inorganic and not an organic material like the different types of resins used in concrete production, it is not affected by UV rays exposure.
Hydroxypropylethyl or methylcellulose offers better application properties. Permeable concrete made with these components has a longer surface drying time, and more ductility.
This additive, compared to the one previously described in Mexican patent application No 962,170, has the following advantages:
The following are some examples of the best way to take this invention in practice, but they should by no means be considered as limitative.